3 ms·

A lightning may contain between 200 and 2000 kWh of energy. There isn't any capacitor or inductor bank that large that could contain this amount of energy that

by zaarn 5y ago

A lightning may contain between 200 and 2000 kWh of energy. There isn't any capacitor or inductor bank that large that could contain this amount of energy that fast. The additional trouble would then be making this energy useful, as capturing this amount of energy safely is not trivial. On top of that, an individual wind turbine is unlikely to be struck often enough to actually make up for the investment of a potential capacitor bank that large.

JohnJamesRambo 5y ago
I’m curious how long it takes a spinning big wind turbine to make 200-2000 kWh of energy? This would properly frame how much energy is in a lightning strike for me.
- mkj 5y ago
  If it's a 12MW turbine it's 10 minutes for 2000kWh. So actually probably not worth bothering with the lightning capture. I'd always thought lighting strikes were more energetic than that.
  - zaarn 5y ago
    What makes lightning strikes so powerful is less the total energy and more the short timeframe it's delivered in.
  - JohnJamesRambo 5y ago
    Fascinating, thanks! A field of turbines is like captured lightning strikes that go on and on.
- s1artibartfast 5y ago
  >Today’s new wind power projects have turbine capacities of about 2 MW onshore and 3–5 MW offshore. Commercially available wind turbines have reached 8 MW capacity, with rotor diameters of up to 164 metres. Depending on the power, each 0.2-2 MW strike is equivalent to the energy produced in a few minutes to an hour of normal operation. https://www.irena.org/wind https://www.irena.org/wind
FooBarBizBazz 5y ago
> A lightning may contain between 200 and 2000 kWh of energy. There isn't any capacitor or inductor bank that large that could contain this amount of energy that fast. Here's the thing though: The Earth-sky system is a big capacitor, which discharges when its dialectric (air) breaks down to form lightning. You can bleed this capacitor slowly before it discharges. I believe that one way to do it is with lightning rods. Supposedly, the spiky tip of the rod concentrates charge, causing a strong local E-field which ionizes the air a little, letting a little current flow. One theory is that this prevents lightning from striking, by preventing too high a potential from building up. If so, we may be able to harvest "lightning power" at relatively high voltages but low currents, using spiky, lightning-rod -type structures, say on top of wind turbines, that trickle into our own capacitors and power electronics. Then, you would see nothing dramatic at all, but maybe, over the course of a few years, you would see a statistically-significant reduction in the number of lightning strikes. At most, maybe you'd occasionally see some St. Elmo's Fire on the spikes. At massive scales you could imagine this messing with the nitrogen cycle -- I believe certain nitrogen compounds important to plants are made by lightning -- but that seems like a pretty far-off concern. Actually, this is a pretty good article. Lots of good work back in the mid 1700s by people like Ben Franklin: https://en.m.wikipedia.org/wiki/Atmospheric_electricity#History https://en.m.wikipedia.org/wiki/Atmospheric_electricity#Hist... Or, check out this delightful website: https://ionpowergroup.com/ https://ionpowergroup.com/. Deep in the bowels of Government Science you can still find people who wear socks with sandals.

by zaarn 5y ago

JohnJamesRambo 5y ago

I’m curious how long it takes a spinning big wind turbine to make 200-2000 kWh of energy? This would properly frame how much energy is in a lightning strike for me.

mkj 5y ago
If it's a 12MW turbine it's 10 minutes for 2000kWh. So actually probably not worth bothering with the lightning capture. I'd always thought lighting strikes were more energetic than that.
- zaarn 5y ago
  What makes lightning strikes so powerful is less the total energy and more the short timeframe it's delivered in.
- JohnJamesRambo 5y ago
  Fascinating, thanks! A field of turbines is like captured lightning strikes that go on and on.
s1artibartfast 5y ago
>Today’s new wind power projects have turbine capacities of about 2 MW onshore and 3–5 MW offshore. Commercially available wind turbines have reached 8 MW capacity, with rotor diameters of up to 164 metres. Depending on the power, each 0.2-2 MW strike is equivalent to the energy produced in a few minutes to an hour of normal operation. https://www.irena.org/wind https://www.irena.org/wind

FooBarBizBazz 5y ago

> A lightning may contain between 200 and 2000 kWh of energy. There isn't any capacitor or inductor bank that large that could contain this amount of energy that fast. Here's the thing though: The Earth-sky system is a big capacitor, which discharges when its dialectric (air) breaks down to form lightning. You can bleed this capacitor slowly before it discharges. I believe that one way to do it is with lightning rods. Supposedly, the spiky tip of the rod concentrates charge, causing a strong local E-field which ionizes the air a little, letting a little current flow. One theory is that this prevents lightning from striking, by preventing too high a potential from building up. If so, we may be able to harvest "lightning power" at relatively high voltages but low currents, using spiky, lightning-rod -type structures, say on top of wind turbines, that trickle into our own capacitors and power electronics. Then, you would see nothing dramatic at all, but maybe, over the course of a few years, you would see a statistically-significant reduction in the number of lightning strikes. At most, maybe you'd occasionally see some St. Elmo's Fire on the spikes. At massive scales you could imagine this messing with the nitrogen cycle -- I believe certain nitrogen compounds important to plants are made by lightning -- but that seems like a pretty far-off concern. Actually, this is a pretty good article. Lots of good work back in the mid 1700s by people like Ben Franklin: https://en.m.wikipedia.org/wiki/Atmospheric_electricity#History https://en.m.wikipedia.org/wiki/Atmospheric_electricity#Hist... Or, check out this delightful website: https://ionpowergroup.com/ https://ionpowergroup.com/. Deep in the bowels of Government Science you can still find people who wear socks with sandals.